Solution of polypyrrolidone in a mixture of chloral hydrate and water, and process of making same



United States Patent O IC SOLUTION- OF lUL-YPYRRQLIDONE llN A MIX- TURE F CHLORAL HYDRATE AND WATER, AND PROCESS OF MAKING SAME William B. Black, Decatur, Ala, assignor to The (lhemstrand Corporation, Decatur, Alan, a corporation of Delaware No Drawing. Filed May 27, E59, Ser. No. 816,986

This invention relates to new compositions of matter. More particularly, the invention relates to new compositions ofmatter comprising polypyrrolidone and solvents therefor.

Polypyrrolidone possesses many excellent properties which make is desirable for utilization in the manufacture of endproducts, such as ribbons, films, fibers, filaments, rods, bristles, lacquers, coatings, shaped articles and the like. Polypyrrolidonecan be convertedinto shaped articles 'in many ways. films or forced through multi-hole spinneret-s to form fibers or filaments. Regardless of the end use to which the polypyrrolidone is to be put, it is generally'more convenient and efiicient to employ the polymer in a solution. This is wellillustrated in textile industry where polypyrrolidone is employed in the formation of fibers and.

filaments, which are manufactured by several methods of spinning, such as melt spinning, dry spinning, and wet pinning.

In the melt spinning method, the polymer is heated to a'hi'gh temperature until it becomes molten, and is thereafter forced through sand packs and the like, and thence through a spinneret from whence it is extruded in filamentary form. This method has, however, many disadvantages, although it is widely used in the industry at the present time in the production of synthetic fibers and filaments. The-high temperatures used in melt spinning require the exercise of extreme care in order to prevent the decomposition of the polymer. Furthermore, the hightemperatures also afiect the chemical and physical characteristics of the polymer and thereby result in a product of inferior quality. In addition to these disadvantages, it is extremely difficult to add tothe molten polymer at such high temperatures compounds such as dyes, anti-static agents, plasticizers and the like.

In the dry spinning method of fiber formation, the polymer is dissolved in a suitable solvent and subsequently extruded from spinneret into a heated atmosphere in order to evaporate the polymer. Even this method, however, has its disadvantages, since during the period of time in which the solvent evaporates, considerable damage may be inflicted on the fibers because of the high heat necessary to bring about solvent evaporation. Another disadvantage of the dry spinning method, and of the melt spinning method also, is the added cost necessary to maintainsuch' high temperatures needed to manufacture the desired end product.

The wet spinning method obivates many of theidis advantages of both melt spinning and dry spinning. I11 order to form filaments by the wet spinning method, the

polymer is dissolved in'a suitable solvent and extruded from -a spinneret into a coagulating bath capable of leaching the solvent from the fibers. Normally, this method may be carried out at temperatures much lower than either the melt spinning or dry spinning methods. If it is desired to use additives, such as dyes, anti-static agents, fire-re tarding agents, plasticizers and the like, in the polymeric solution, they may be incorporated therein Without the danger of decomposition or seriously allecting the propertiesof the-end product where the wet spinning method of'filamentaryformation is employed. It is much easier For example, it may be cast into Patented Oct. 10, 196.1.

2. to introduce such additivesinto a solutionthan toIintroa duce them into a molten composition. -Then again, solu-t tions are much easier to handle. dur-ingprocessing, andiin. many cases may be stored for long periods of time .with; V out a change'of physical andchemical properties. It;.is much easier to cast afilm from a solution than to cast it from a molten composition. It is readily apparent,.therefore, that solutions of polypyrrolidone possess manydis tinct advantages over molten compositions in the manu-. facture of end products.

Accordingly, it is a primary object of the, present invention to provide new and useful compositionsof mat ter comprising polypyrrolidone It is another object of. this invention to provide solutions ofpolypyrrolidone. It is a further object of the invention to provide solutions; ofpolypyrrolidone which may be converted into shaped articles, such as ribbons, films, filaments, fibers, rods, bristles and the like. It is still another object of the "in.--; vention to provide a. process for the preparation of poly-.. pyrrolidone solutions. Other objects andadvantagesof; the instant invention will be.readily apparent from the: description thereof which follows hereafter.

In general, the objects of thepresent invention .-are accomplished by'dissolving' polypyrrolidone in chloral hydrate or a mixed solvent containing chloral hydrate and? water.

When employing amixed solvent in the practiceof the-- present invention, Water may be utilized with chloral hy drate .within a broad range, based on the total weight'of" the solvent mixture. As much as 99 percent chloralhy, drate and 1 percent of water may be employed and the; beneficial effects of the water are attained. However, as 1. a practi'cal matter, a solvent containing from about 5 :to. 10 percent water and as much as 70 percent water res. sults in a solvent mixture capable of dissolving polypyrrolidone to give solutions which are valuable for being. shaped into articles such as filaments, fibers, rods,-bristles, films, coatings, etc. Water is advantageous in that solu-,'

tions containing a higher percentage of polymer can: be:

prepared than in chloral hydrate alone. Furthermore, water reduces the viscosity of asolution. at a given poly mer content. Water further results in solutionswhichr. are stable at room temperature, since chloral hydrate, which has a meltingpoint of about-51.7 C., will IlOt." crystallize out when water is present.

It will be readily apparent to those skilled incthe that polypyrrolidone can be dissolved in the solventsoi the. present inventionin widely varying concentrations. The concentration of any particular polymer in any para ticular solvent depends upon the nature of thepolymer; the solvent employed and the temperature,which insturna. effect the viscosity of the solution. When the solutionisz to be employed in the manufacture of fibers and filaments, as much as 40 percent of the polymer, based Bathe-totals weight of the solution, may be dissolved in the. solvents:. of this invention. Whileit is preferred to employ. 15.10 35 percent of thepolymer, based onthe totalweightofif the solution, when the-'solutionisto beused in-.the prepara- I tion of fibers and filaments,.,it-is to beunderstoodithat as little as 5 percent unless and more than. .40 percent-of polypyrrolidone may be. dissolved in lZh6-jS0lVIllS. 0fthlS' invention when the: solution isto1be usediforother-pur poses, such as a coating or a lacquer and the like; or-"- when lower or higher molecular-weight polypyrrolidones are dissolved in the solvents.

The solvents of this invention readily;dissolve.polypyr rolidone within a wide. range of temperature depending, on the nature of the polymer, the.concentrationthereofiin the solvent and the nature of the solvent itself Although i temperatures within a range of 55 C. to.80 C.. areprefer-red as a practical matter in bringing about solution,

temperatures as low as 25" C. and as high as the boiling point of the polymer/solvent mixture may be employed to bring about the solution. Heating of the polymer/ solvent mixture is preferably accomplished on a water, glycerine or oil bath. However, other means may be employed. If desired, agitation or stirring of the mixture may be employed during heating while a solution is being formed at low temperatures, although it is to be understood that it is not always necessary or critical.

If it is desired to produce shaped articles from the polypyrrolidone compositions of the present invention which have a modified appearance and modified properties, various agents to accomplish these efiects may be added to the polymer solution prior to fabrication of the articles without having any ill eifects thereon. Such agents may be plasticizers, pigments, dyes, anti-static, agents, fire-retarding agents, and the like.

Polypyrrolidone soluble in the solvents of this invention may be prepared by various processes. Generally, however, polymeric pyrrolidone is prepared by polymerizing 2-pyrrolidone in the presence of a catalyst or a catalyst and activator at a temperature in a range of 70 C. to 100 C. However, since the polymerization reaction proceeds well in a range of 20 C. to 70 C., these temperatures are preferred in carrying out a polymerization procedure.

In the preparation of polypyrrolidone, a large number of known catalysts are available to catalyze the polymerization. Among such catalysts, there may be named the alkali metals, namely, sodium, potassium and lithium, as well as the hydrides, hydroxides, oxides and salts of the alkali metals, that is such salts as sodium, lithium and potassium pyrrolidone. Organic metallic compounds, preferably those which are strongly basic, may be used as catalysts, too. Examples of such compounds are lithium, potassium and sodium alkyls and aryls of the alkali metals, such as sodium phenyl. Another suitable catalyst is sodium amide. The alkali hydrides, however, are the preferred catalysts since a distinct advantage is obtained by their use. Sodium hydride, for example, does not react in the polymerization mixture to form water, which, as is Well-known, has a deleterious effect on pyrrolidone polymerization. Where water-forming catalysts, such as sodium hydroxide, are employed as a catalyst, all water of reaction must be removed from the reaction mixture by vacuum distillation or other means in order for polymerization to proceed at a reasonable rate. Generally, the catalysts may be employed in a range of 0.002 to 0.25 chemical equivalent based upon one mole of monomeric pyrrolidone in carrying out a polymerization reaction.

Although polypyrrolidone having acceptable properties can be prepared by using a catalyst alone, it is preferable to employ an activator in conjunction with any of the catalysts mentioned above, since the polymer pre pared in the presence of both a catalyst and activator has greatly improved properties over polypyrrolidone prepared in the presence of a catalyst alone. Among the compounds which may be employed as activators, there may be named the acyl compounds, such as acetyl pyrrolidone, acetyl morpholone, and the like; lactones, such as gamma butyrolactone, and the like; alkyl esters of monoand dicarboxylic acids, such as ethyl acetate, ethyl oxalate, and the like; the esters of polyhydric alcohols, such as ethylene glycol diacetate and the like; and nitrogen dioxide and organic nitriles having the general formula:

'wherein R is selected from the group consisting of alkyl groups containing 1 to carbon atoms, haloalkyl groups containing 2 to 10 carbon atoms, nitroalkyl groups containing 2 to 10 carbon atoms, aralkyl groups containing 7 to 10 carbon atoms, and alkoxyalkyl groups containing 3 to 12 carbon atoms. Among the nitrites falling into the general formula set out above, there are methyl nitrite, ethyl nitrite, n-propyl nitrite, iso-propyl nitrite, nbutyl nitrite, iso-butyl nitrite, amyl nitrite, iso-amyl nitrite, hexyl nitrite, heptyl nitrite, octyl nitrite, nonyl nitrite, decyl nitrite, and their isomeric forms, and the like; haloalkyl nitrites, such as 2,2,2-trichloroethyl nitrite; the dihaloalkyl nitrites, such as 2,2-dichloroethyl nitrite, 2,2 dichloropropyl nitrite, 2,2-dichlorobutyl nitrite, 2,2-dichloroamyl nitrite, 2,2-dichlorohexyl nitrite, 2,2-dichloroheptyl nitrite, 2,2-dichlorooctyl nitrite, 2,2-dichlorononyl nitrite, 2,2-dichlorodecyl nitrite, and the like monochloroalkyl nitrites, their isomeric forms, and the like; nitroalkyl nitrites, such as 2-nitroethyl nitrite, Z-nitropropyl nitrite, 2-nitrobutyl nitrite, Z-nitroamyl nitrite, 2- nitrohexyl nitrite, 2-nitroheptyl nitrite, 2-nitrooctyl nitrite, 2-nitrononyl nitrite, 2-nitrodecyl nitrite, and their isometric forms, and the like; aralkyl nitrites, such as benzyl nitrite, Z-methylbenzyl nitrite, B-methylbenzyl nitrite, 4-methylbenzyl nitrite, 2-ethylbenzyl nitrite, 3- ethylbenzyl nitrite, 4-ethylbenzyl nitrite, 2-propylbenzyl nitrite, 3-propylbenzyl nitrite, 4-propylbenzyl nitrite, 2- methyl-3-ethylbenzyl nitrite, 2-methyl-4-ethylbenzyl nitrite, Z-rnethyl-S-ethylbenzyl nitrite, 2-methyl-6-ethylbenzyl nitrite, 3-methyl-4-ethylbenzyl nitrite, 3-methyl- S-ethylbenzyl nitrite, 3-rnethy1-6-ethylbenzyl nitrite, 4- methyl-2-ethylbenzyl nitrite, 4-methyl-3-ethylbenzyl nitrite, 2,3-dimethylbenzyl nitrite, 2,4-dimethylbenzyl nitrite, 2,5-dimethylbenzyl nitrite, 2,6-dimethylbenzyl nitrite, 3,4-dimethylbenzyl nitrite, 3,5-dimethylbenzyl nitrite, and the like; and alkoxy-alkyl nitrites, such as 2- methoxyethyl nitrite, 2-ethoxyethyl nitrite, 2-propoxyethyl nitrite, Z-butoxyethyl nitrite, 2-pentoxyethyl nitrite, 2-hexoxyethyl nitrite, 2-heptoxyethyl nitrite, 2- octoxyethyl nitrite, 2-nonoxyethyl nitrite, 2-decoxyethyl nitrite, and their isomeric forms and the like.

Another excellent polymerization activator is carbon disulfide. Silicon halides and organic silicon halides having the general formula:

wherein R is a saturated or unsaturated aliphatic or aromatic hydrocarbon radical containing 1 to 10 carbon atoms, a saturated or unsaturated aliphatic or aromatic halogenated hydrocarbon radical containing 1 to 18 carbon atoms, and X is a halogen, z is an integar from 1 to 4 inclusive, and y is equal to 4-z, wherein R may be similar or dissimilar radicals, may also be employed to activate polymerization of 2-pyrrolidone. Among the silicon halides and organic silicon halides there may be named tetrachlorosilane, alpha,beta-dichloroethyltrichlorosilane, bis (chloromethyl) methylchlorosilane, butyltrichlorosilane, chloromethylrnethyldichlorosilane, dichloromethyldimethylchlorosilane, diethyldichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane, ethyltrichlorosilane, methyltrichlorosilane, phenyltrichlorosilane, propyltrichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, the iodoand bromoforms of the above compounds, and many others. The trihalides of phosphorous, aluminum, bismuth and antimony, the tetrahalides of titanium, tin, zirconium and lead, and the pentahalides of antimony and phosphorous are also useful as activators in the polymerization of 2-pyrrolidone. Such compounds include aluminum trichloride, aluminum tribromide, aluminum triiodide, stannic tetrachloride, stannic tetrabromide, lead tetrachloride, zirconium tetrachloride, bismuth trichloride, bismuth tribromide, antimony trichloride, antimony tribrornide, antimony triiodide, antimony pentachloride, antimony pentaiodide, antimony pentafluoride, and the like. The phosphorous halides include phosphorous tribromide, phosphorous pentabromide, phosphorous trichloride, phosphorous pentachloride, phosphorous triiluoride, phosphorous pentafluoride, phosphorous triiodide, and the like. Generally, in the preparation of polypyrrolidone wherein both a catalyst and activator are employed to bring about poly- E!) a merization, the activator is utilized in a range of 0.0001 to 0.075 chemical equivalent of activator, based upon one mole of 2-pyrrolidone.

The polypyrrolidone soluble in the solvents of the invention is prepared by simple polymerization methods. It can be prepared readily by well-known solution, emulsion, suspension or bulk polymerization procedures. The solution and emulsion polymerizations may be either batch, semicontinuous or continuous methods. When solution polymerization is employed, the monomer is dissolved in a solvent such as 1,4-dioxane, the desired catalyst or activator, or both, added to the solution, and the polymerization carried out under the proper conditions. Well-known solution polymerization apparatus is suitable for preparing the polypyrrolidone described herein. Where either emulsion or suspension polymerization techniques are employed to prepare the polymer, the monomer containing the catalyst is dispersed in a nonsolvent, such as petroleum ether, and an emulsifying agent, then added to the dispersion. Subsequently, the desired activator is injected into the mixture and the dispersion is polymerized until the reaction is complete. At this time, suitable coagulant is added to the polymerization mixture in order to precipitate the polymer. A suitable emulsifying agent is sodium lauryl sulfate, and the suitable coagulant is phosphoric acid.

Polypyrrolidone prepared in accordance with the procedures set forth herein-above has a melting point of about 260 C. and a specific viscosity of from about 0.3 to 4.5 or more. It is thus particularly adapted for the manufacture of shaped articles such as filaments, fibers, films, rods, bristles, and the like. Lower molecular weight polymers prepared in the same manner are suitable for the preparation of coatings or lacquers.

The following examples are intended to illustrate the new compositions of this invention more fully but are not intended to limit the scope of the invention, for it is posf sible to effect many modifications therein. In the examples, all parts and percents are by weight unless otherwise indicated.

EXAMPLE I To a 50 grams sample of essentially anhydrous 2- pyrrolidone there was added under a nitrogen atmosphere 0.5 gram of sodium hydride catalyst. When the evolution of hydrogen gas was completed, this mixture was stoppered to protect it against the atmosphere and permitted to stand at about 25 C. for 4 days. The polymer was recovered by breaking up the cake, grinding it in a Wiley mill, and washing the powder, first with water, then with acetone, in a Waring Blendor. The polymer was subsequently air-dried to constant Weight and had a specific viscosity of 0.503 (determined on a 0.5 percent solution of the polymer in 90 percent formic acid at 25 C.).

0.5 gram of the polypyrrolidone so prepared was mixed with 9.5 grams of chloral hydrate. The mixture was stirred with heating to a temperature of 55 C. to form a viscous, completely colorless, clear solution containing 5 percent concentration of polymer based on the total weight of the solution. The solution was stable at 55 C. On cooling to room temperature, the solvent, chloral hydrate, which has a melting point of 51.7 C. crystallized after about 30 minutes. The solution so formed was suitable for the formation of light films or coatings.

EXAMPLE II A solvent'mixture was prepared containing 2 grams (66 /3 percent by weight) of chloral hydrate and 1 gram (33 /5 percent by weight) of water. To the mixed solvent there was added 2 grams of the polypyrrolidone prepared in accordance with the procedure of Example I.

The mixture was stirred and heated to 100 C. in a water 40 percent by weight of the polymer, based on the total weight of the solution. This solution was stable at room temperature (about 25 C.) after standing overnight.

' EXAMPLE In 0.6 gram of the polypyrrolidone prepared in accordance with the procedure of Example I was mixed with 3 grams of chloral hydrate and heated with stirring in a water bath. to a temperature of 100 C. where the poly- EXAMPLE IV A mixed solvent was prepared containing 2 grams (66 /3 percent by weight) of chloral hydrate and 1 gram (33 /3 percent by weight) of water. To this mixed solvent there was added 0.6 gram of the polypyrrolidone prepared in accordance with the procedure of Example I. The mixture was heated with stirring to a temperature of 60 C. where the polymer readily dissolved to form a clear, colorless solution which remained stable on standing at room temperature (about 25 C.) overnight. This solution was much less viscous than the solution in the foregoing example wherein chloral hydrate was used alone, although it contained the same concentration (17 percent by weight, based on the total weight of the solu-. tion) of polymer. The solution so formed was suitable for the formation of filaments and fibers by both wet spinning and dry spinning methods.

EXAMPLE V To a 50 gram sample of essentially anhydrous 2- pyrrolidone, there was added under a nitrogen atmosphere sodium hydride catalyst in a ratio of 1:100 parts catalyst to monomer by weight. When the evolution of hydrogen gas was completed, there was added 0.448 gram of carbon disulfide activator. The reaction mixture was stirred vigorously and stoppered and permitted to stand at about 25 C. for 4 hours. The reaction mixture was then ground up with water in a Waring Blendor and the polymer filtered. The filter cake was washed with acetone and subsequently air-dried to constant weight. The polymer had a specific viscosity of 0.40 (determined on 0.5 percent solutions of the polymer inpercent formic acid at 25 C.).

A mixed solvent was prepared containing 8 grams (80 percent by weight) of chloral hydrate and 2 grams (20.

percent by weight) of water. 2 grams of the mixed solvent so prepared and 0.5 gram of the polypyrrolidone prepared in accordance with the procedure above were mixed together with stirring at room temperature (about 25 C.) to form a solution containing 20 percent of polymer based on the total weight of the solution. The polymer was completely dissolved in the solvent after stirring for a period of about 10 minutes. The solution so formed was suitable for the formation of fibers and filaments by both wet and dry spinning methods, as well as suitable for the formation of films.

EXAMPLE VI A series of solutions was prepared containing 35 percent by weight, based on the total weight of each solution, of polypy-rrolidone. The solvents employed were mixed solvents containing varying amounts of chloral hydrate and water. The polymer was prepared as follows: To grams of essentially anhydrous Z-pyrrolidone there was added under a nitrogen atmosphere 1 gram of sodium hydride catalyst. When the evolution of hydrogen gas was completed, this mixture was stoppered to protect it against the atmosphere and permitted to stand for 5 days at room temperature (about 25 C.). There:

7 after, the polymer so formed was filtered and there was obtained a yield of 16 grams (16 percent of theoretical yield). The polymer had a specific viscosity of 0.703 (determined on 0.5 percent solutions of the polymer in 90 precent formic acid at 25 C.).

To 3.25 grams of each of the mixed solvents, there was added 1.75 grams of the polymer and the resulting mixtures were put into a water bath at 80 C. The percent by weight of chloral hydrate and water, based on the total weight of each mixed solvent, is set out in the following table.

Table I Percent by Percent by weight of weight of chloral hydrate water The polymer/solvent mixtures formed clear, colorless solutions suitable for the formation of filaments and fibers by either wet or dry spinning methods.

EXAMPLE VII Table I I Percent by Percent by weight of weight of chloral hydrate water The solutions were prepared by dissolving 0.75 gram of the polypyrrolidone in 4.25 grams of each of the above solvent mixtures. The polymer/solvent mixtures were then put on a water bath at 80 C. for about 5 minutes where the polymer readily dissolved to form completely clear and colorless solutions which remained stable on cooling to room temperature (about 25 C.). The solutions so formed were suitable for the formation of shaped articles, such as filament, fibers, films and the like.

Polypyrrolidone prepared with other catalysts and activators and having varying molecular weights and viscosity values gave like results when dissolved in the new solvents of this invention.

The new compositions of this invention present many advantages. For example, solutions of polypyrrolidone may be easily prepared on existing equipment without detailed and elaborate procedures. The chloral hydrate which is employed as a solvent herein is readily available and reasonably inexpensive. When water is used with the chloral hydrate in a mixed solvent, numerous other advantages are attained. For example, solutions containing a higher concentration of polymer can be prepared wherein water is employed in the mixed solvent. Furthermore, use of water reduces the viscosity of a given concentration of polymer in any particular solvent mixture. In addition, use of water results in a less expensive solvent. Another important advantage in using a mixture of water and chloral hydrate to dissolve polypyrrolidones such as those described hereinabove is that the water permits the preparation of solutions which are stable as low as room temperature (about 25 C.) because the chloral hydrate which has a melting point of 5 1.7 C. will not crystallize out when water is present.

Polymeric solutions made with the new solvents of this invention are clear and colorless, and products or shaped articles prepared therefrom exhibit good color characteristics. Furthermore, in preparing solutions of polypyrrolidone the new solvents of this invention may be employed without elaborate safety percautions and they have no effect upon the desirable chemical and physical properties of the polymer dissolved therein. Numerous other advantages of the compositions of this invention will be readily apparent to those skilled in the art.

It will be understood to those skilled in the art that many apparently widely diflierent embodiments of this invention can be made without departing trom the spirit and scope thereof. Accordingly, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A new composition of matter comprising polypyrrolidone and a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and up to 70 percent water, based on the total weight of said mixed solvent.

2. A new composition of matter as defined in claim 1 wherein the solvent is chloral hydrate.

3. A new composition of matter as defined in claim 1 wherein the solvent contains chloral hydrate and water.

4. A new composition of matter comprising 5 to 40 percent, based on the total weight of the composition, of polypyrrolidone and a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and from 5 to 70 percent water, based on the total weight of said mixed solvent.

5. A new fiber-forming composition of matter comprising 15 to 35 percent, based on the total weight of the composition, of polypyrrolidone, having a. specific viscosity of at least 0.3, and a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and 5 to 70 percent water, based on the total weight of said mixed solvent.

6. A new composition of matter comprising 5 percent, based on the total weight of the composition, of polypyrrolidone and chloral hydrate.

7. A new fiber-forming composition of matter comprising '17 percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of 0.503, and a mixed solvent containing chloral hydrate and 33 /3 percent water, based on the total weight of said mixed solvent.

8. A process for preparing a new composition of matter comprising mixing polypyrrolidone in a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and up to 70 percent water, based on the total weight of the mixed solvent, and heating the mixture to a temperature in a range of 25 C. to the boiling point of the mixture to form a homogeneous solution.

9. The process as defined in claim 8 wherein the solvent is chloral hydrate.

10. The process as defined in claim 8 wherein the solvent contains chloral hydrate and water.

11. A process for preparing a new composition of matter comprising mixing 5 to 40 percent, based on the total weight of the composition, of polypyrrolidone in a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and 5 to 70 percent water, based on the total weight of the mixed solvent, and heating the mixture to a temperature in a range of 25 C. to the boiling point of the mixture to form a homogeneous solution.

12. A process for preparing a new fiber-forming composition of matter comprising mixing 15 to 35 percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of at least 0.3, and a solvent selected from the group consisting of chloral hydrate and a mixed solvent containing chloral hydrate and 5 to 70 percent water, based on the total weight of the mixed solvent, and heating the mixture to a temperature in a range of 25 C. to the boiling point of the mixture to form a homogeneous solution.

13. A process for preparing a new fiber-forming composition of matter comprising mixing 17 percent, based on the total weight of the composition, of polypyrroiidone, having a specific viscosity of 0.503, and chloral hydrate, and heating the mixture to a temperature of 100 C. to form a homogeneous solution.

14. A process for preparing a new fiber-forming composition of matter comprising mixing -15 percent, based on the total weight of the composition, of polypyrrolidone,

References Cited in the file of this patent UNITED STATES PATENTS 2,752,320 De Witt June 26, 1956 FOREIGN PATENTS 205,015 Australia Nov. 11, 1954 218,129 Australia Jan. 16, 1958 

1. A NEW COMPOSITION OF MATTER COMPRISING POLYPYRROLIDONE AND A SOLVENT SELECTED FROM THE GROUP CONSISTING OF CHLORAL HYDRATE AND A MIXED SOLVENT CONTAINING CHLORAL HYDRATE AND UP TO 70 PERCENT WATER, BASED ON THE TOTAL WEIGHT OF SAID MIXED SOLVENT. 